About Optics & Photonics TopicsOSA Publishing developed the Optics and Photonics Topics to help organize its diverse content more accurately by topic area. This topic browser contains over 2400 terms and is organized in a three-level hierarchy. Read more.

Topics can be refined further in the search results. The Topic facet will reveal the high-level topics associated with the articles returned in the search results.

Abstract

A double sampling method enabling to have excellent channel uniformity and high in-band energy efficiency is firstly proposed for the design of an ultrahigh-channel-count fiber Bragg grating (FBG), which is based on the simultaneously utilization of an amplitude-assisted phase sampling (AAPS) function and a phase-only sampling (POS) function. As
examples, two typical 10-dB FBGs with a length of 12 cm, dispersion of - 1360ps/nm, channel spacing of 0.8 nm, and a consecutive 135- and 405- channels are numerically designed. The maximum index-modulations required are about 0.8×10-3, and 1.3×10-3, respectively. Compared with the proposed method, the other two kinds of double sampling schemes by utilizing either the double AAPS (i.e., AAPS+AAPS) or the double POS (i.e., POS+POS) have also been introduced for the design of the multichannel FBGs. Fabrication tolerances to the designed 135-channel FBG obtained with the AAPS plus POS method are numerically investigated.

Design results for a 135-channel double sampled FBG (AAPS+POS). (a) grating index
profile, the inset shows the fine index profile within a region of 1mm, (b) grating phase profile, the inset shows the fine phase profile within a region of 1mm, (b) reflection and group delay spectra, the insets show the spectra at the wavelengths of 1509 nm, 1545 nm and 1581 nm, respectively.

Design results for a 405-channel double sampled FBG (AAPS+POS). (a) Grating index
profile, the inset shows the fine index profile in a distance of 1mm, (b) grating phase profile, the inset shows the fine phase profile in a distance of 1mm, (b) reflection and group delay spectra, the insets show the spectra at the wavelengths of 1420.5 nm, 1492.5 nm, and 1564.5 nm, respectively.

Numerical results for the required fabrication tolerance of the 135-channel FBG
(AAPS+POS). (a) Reflection spectra of the central three channels with different amplitude and phase perturbations, the inset shows the top of the central channel spectra, (b) group delay spectra of the central three channels with different amplitude and phase perturbations, the inset shows the group delay ripples of the central channel spectra.